Add an SPDX identifier as well as a copyright notice pursuant to section
6.d. of the Trust Legal Provisions to all ASN.1 modules in the tree
which are derived from IETF Documents.
Section 4.d. of the Trust Legal Provisions requests that each Code
Component identify the RFC from which it is taken, so link that RFC
in every ASN.1 module.
Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>